To improve patient safety, the Institute of Medicine recommends that health care organizations "implement mechanisms of feedback and learning from error." But little is known about how health care organizations learn. Therefore, we propose two studies, one cross-sectional and the second longitudinal, of organizational learning in hospitals and their pharmacies. We plan to study a major cancer center, an urban community hospital, and a tertiary care teaching hospital. We define organizational learning as the process in which decision-makers weigh past experience as a basis for changing the routines that will guide future behavior (Levitt and March, 1988). Using qualitative research methods, we will examine how hospitals define, collect information about, and learn from safety-related medication events. We use the term "safety-related medication events" to include actual or potential adverse drug events, errors, and near misses, but to exclude idiosyncratic drug reactions. Our long-term objectives are to identify organizational conditions that affect organizational learning and to assess the feasibility of learning from near misses in hospitals. Our specific aims are: 1. To describe four fundamental processes that contribute to organizational learning from safety-related medication events: event definition; data collection; analysis and interpretation; and decision-making and implementation. 2. To identify the key organizational factors that influence these four processes. Based on our pilot study and organization theory, these factors may include: (a) incentives, (b) communication channels, (c) attention allocation, (d) task specialization and coordination, and (e) the distribution of decision-making authority. 3. To describe how the key organizational factors identified in aim 2, both individually and in combination, affect the four fundamental processes of learning described in aim 1.4. To generate hypotheses that examine how different methods of defining events and gathering and analyzing data interact to influence how hospitals learn from experience. 5. To assess how the implementation of close-call reporting in project 5 affects the ability of a hospital unit to learn. 6. To develop practical guidelines for identifying and removing critical organizational barriers to learning. 7. To develop alternative models for designing a close-call reporting system and specify the organizational conditions that support them.